Current systems for web-based purchasing or mobile purchasing (e.g., via an internet-enabled smartphone or similar mobile device) incorporate an Application Programming Interface (API) to manage the exchange of information between a broad variety of client-side and merchant-side systems. APIs may be created by the parties involved in the transactions, and may to some extent be standardized, as within a network of participating vendors affiliated with each other and with a client-side platform. If, for example, the user of a mobile device wishes to purchase multiple items from multiple third-party vendors outside a vendor network, the simultaneous invocation of multiple diverse APIs by a mobile application may slow or disrupt other activity on the mobile device. It may therefore be desirable for a mobile purchase system to simultaneously manage multiple purchases, from participating and third-party vendors, in real time without disrupting the experience of the end user.